Korg Forums

[mackbaz]

Ok, so my replacement is not even a half of a year old and the tube has gone out? I played last night just fine with no cutouts or anything.. start it up today and it won't play when the amp modeling is turned on. Is the tube actually bad already, or is there something I can do?

[Jampaq]

I have a similar problem - been Googling for a while about it, but not too many people seem to have this issue, I guess? Mine is mainly cut out, but sometimes I can tap it and get it back...

[SanderXpander]

If it's not a bad contact it could be the tube itself is broken. They're fragile. There's a reason they tried to get rid of them in amp design.
That said, I don't know how handy you are but a 12AX7 (I think that's the one in there?) is not actually very expensive.

[keyboard komuso]

If you replace it yourself though I believe you're voiding the warranty. In the manual it says to bring it to an authorized service center. Kind of ridiculous I think. Seems simple enough to replace from the front panel. Why have to spend the money for an "expert" to do it. Not to mention most likely being overcharged for the tube. It's a given that at some point the tube will burn out. It should really be an owner replaceable part.
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"Music is the space between the notes." - Claude Debussy

[flyingace]

I agree it should be a user serviceable part. I disagree that they are all that fragile and the bit about the amp makers trying to stop using them...

I have 12 tubes in my guitar amp. I travel with it, it takes a pounding and not once have I lost a tube. I carry spares, coz they do go out after a period of time and they are sensitive to major power spikes, but the sensitive keyboard circuit boards would be damaged from that kind of jolt.

They have been known to come from factory faulty as well. Korg uses a good brand calld RUBY in the SV-1. I originally thought I'd like to put my usual TungSol in there but when I saw it was a RUBY, I'm ok with that.

It would be nice if it was user serviceable though. Just a heads up, I do not believe the way to remove it is to use the front panel cover. I think that's just cosmetic and you have to take the keyboard apart to actually remove it. If I'm wrong, I'd be happy to hear it.
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Inspired by my Roland Jupiter 80 and SV-1 73, Fender Strats, Teles and Fender Amps, Taylor Acoustic. I am also an avid Ukulele player!

[SanderXpander]

I worked in a guitar shop for a while. The amount of tubes sold was huge compared to the amount of transistor amp repairs we had. I have nothing against tubes by the way, I love the sound and I have had zero problems with the tube in my Triton Extreme.

[mackbaz]

so i finally got it replaced.. its not easy. I actually took it to a dealer and he thought he could just pop it right out.....nope. The whole keyboard has to come apart to get enough leverage on the thing to get it out. The guy had take apart about 50 keyboards before and said this was by far the worst when it comes to assembly. Pretty sure my warranty is voided now, but to be honest I don't care. It took one day to get it fixed. Last warranty repair took 2 months. What a joke.

[ToyTech]

Maybe a late follow-up, but thought i'd add my 2 cents
I'm a service Tech for Korg products (amongst many other brands), but i DON'T work for Korg directly.

YES - the tubes often die/crack/explode - not sure why, bad batching? I've replaced almost 10 in the past year.
NO - The tube cannot be changed from the front!
YES - the valve "window" screws still do need to come out, as they hold the valve-unit (PCB & cradle) in place underneath the front panel.
YES - The keyboard needs to be somewhat dismantled, but not as big a job as previous posts have suggested, Approx 25 screws on the base board gets the keyboard opened and into the valve unit within 10-15 minutes.
YES - Opening the keyboard/changing the valve yourself VOIDS warranty !!!

Hope that helps in future?

[mackbaz]

The issue wasn't finding the screws to take out, it was accessing the tube, which from our perspective required taking the keybed out. I realized this voided the warranty, but honestly the warranty isn't worth much to me, as any time I've used it, it takes at least a month to get a keyboard back from warranty repair... and thus far hasn't been any better. $46 bucks at a local shop bested this so called warranty by far.

[ToyTech]

Forgot to also add:

YES - there is an alignment procedure once the valve is replaced, to match the levels between "regular" and "amp modeler" modes..

NO - It isn't always a broken valve when the "cutout fault" occurs, there can be any assortment of issues with input/output components & connections around the valve drive board for a start.

[ShaunKorg]

Its a good point about the warranty. Unless you can get a loaner board its more trouble than its worth to not try and fix things yourself.

[ToyTech]

I agree with a comment above, that the valve SHOULD be user-accessable.

It's actually ridiculous that it's not and end-user changable part, in fact as a service-tech, i'd prefer that valves, backup batteries, ram upgrades COULD be performed by the home user, 'coz i'm sick of it hehehehee, but that's marketing for ya ;-(

[ShaunKorg]

I posted a question on Harmony Central forums about someone making a keyboard repair guide but it didn't get much response.

Things like guitars are pretty straight forward to work on, but I don't know anything about keyboard repair. I hear stories about people swapping keybeds, adding keys and stuff like that, but I wouldn't know where to begin.

Obviously not all boards are the same, but I wish someone would make a written or video guide about basic keyboard repair.

[ToyTech]